1. Field of the Invention
The present invention relates to a dishwasher, and more particularly, to a dishwasher and a controlling method thereof capable of obviating blockage of spray holes in the spray arms of the dishwasher by impurities during a wash cycle.
2. Description of the Related Art
A dishwasher is an apparatus that sprays wash liquid at high pressure to wash impurities from dishes placed on its racks.
A dishwasher includes a tub forming a wash compartment, and a sump installed at the bottom of the tub for storing wash liquid. The door of the dishwasher has a detergent cup formed in its inner panel for filling with a predetermined amount of detergent.
The dishwasher also includes a wash pump installed inside the sump for pumping wash liquid to the spray arms. The wash liquid pumped to the spray arms is sprayed at high pressure from spray holes formed at the ends thereof.
The wash liquid sprayed under high pressure collides with the surfaces of dishes and causes food residue and other impurities on the dishes to be removed and fall to the floor of the tub.
Also, a lower spray arm that sprays wash liquid upward is provided above the sump, an upper spray arm is disposed roughly in the center of the tub, and a top spray arm IS formed at the ceiling of the tub to spray wash liquid downward.
FIG. 1 is a flowchart of a controlling method for a dishwasher according to the related art.
First, after dishes to be washed are placed in an upper and/or lower rack of the dishwasher, the door is closed and the power is switched on.
When power is applied to the dishwasher, wash liquid is sprayed through the spray arms and nozzle. The spray arms rotate to spray dishes, removing them of impurities.
Specifically, a user selects a desired wash course and inputs operating commands in step S10. Then, wash liquid enters the sump in step S11, and a wash motor for pumping wash liquid stored in the sump under high pressure is operated in step S12. Especially, the wash motor is operated at the same rpm for both an upper and a lower wash cycle of the dishwasher.
Wash liquid is sprayed from the spray arms in step S13, and a cycle for removing impurities from the stored dishes is implemented in step S14.
Some dishwashers according to the related art employ a filter installed at the lower end of the tub, in order to prevent large-sized impurities, such as watermelon seeds and corn kernels, that are washed from dishes from entering the spray arms.
However, although the filter can prevent clogging of the spray arms and nozzle, impurities that accumulate on the filter and are not discharged automatically, so that a user must take the trouble of manually removing them.
Also, the spray holes of the spray arms and nozzle may be designed to be larger in size than a certain size of impurities. Although this may prevent clogging of the spray holes, the water pressure of the sprayed wash liquid is weakened. To compensate, the capacity of the wash pump must be increased.